Electric regulator incorporating piled up carbon elements



Jan. 1, 1952 M. Musso 2,581,280

ELECTRIC REGULATOR INCORPORATING PILED UP CARBON ELEMENTS Filed May 18,1949 Inventor MARCEL MUSSO Agent Patented Jan. 1, 1952 UNITED STATESPATENT OFFICE ELECTRIC REGULATOR IN CORPORATING PILED UP CARBON ELEMENTSMarcel Musso, Paris, France Application May 18, 1949, Serial No. 93,982In France May v2.1, 1948 Claims.

larly applicable to regulating systems including thin piled up discsmade of carbon compounds whereby the variations in pressure exerted onsaid piled up discs are obtained through automatic devices acting underthe control of any electrical quantity, suchas voltage, current, etc.Where in the following description the terms voltage and current areused, they are meant to refer to any electrical quantity to be regulatedby, and influencing, the systems referred to.

The known regulating systems include means act directly or otherwise onthe piled up discs through the armature of an electromagnet that isurged electromagnetically in a direction in opposition to a spring sothat the resulting force exerted on the piled up discs is equal to thedifierence between the action of the electromagnet and that of thespring.

The movement of the armature of the electromagnet may be a translationalor rotational one; in either case, the attractive force of theelectromagnet depends on the square of the induction force, on thecross-sectional area of the gap and also on the inverse value of thelength of said gap. It will consequently vary with the relative positionof the armature and will also depend on all the circumstances that maybring about an accidental change in the induction value, such as thetemperature that makes the resistance vary in the wire forming theelectromagnet coil.

Similarly, any change due to wear, temperature or other reasons maymodify the distance between the armature and the piled up discs andconsequently modify the action of the armature.

My invention has for its object a method according to which thedisplacements of the movable set do not cause a change in the force orthe torque acting on said movable set through the electrical quantitythat governs the operation of the arrangement.

My invention has also for its object an arrangement wherein theresultant of the forces applied to the piled up discs no longer dependson the initial position of the element compressing or releasing thepile.

According to a further the arrangement may be energized not only throughdirect current as in priorarrangements,

but also through one-phase or polyphase alternatingcurrent and even incertain cases by means of currents having difi'erent characteristics.

object of the invention,

According to a still further object of my invention, variationsintemperature have no efiect or practically no effect, due to theelectromotive principle'used, on the force or torque which act on themovable set .through the electrical quantity governing said arrangement.

My invention is also characterized by the fact that the pressure isexerted on the piled up carbon discs through development ofelectrodynamic forces. According to a preferred embodi- .ment, themovable set is constituted by the rotor of an electric motor.

,I will now describe embodiments of my invention in greater detail, butmany changes and modifications of the embodiments shown may 'be madewithout departing from the spirit of the invention.

The specification is accompanied by a drawing in which:

Fig. 1 is an axial diagrammatical cross section of a regulator accordingto my invention.

Fig.2 is an axial .cross section of a further embodiment of a regulatoraccording to the inven-- tion.

Fig. 3 is a detail view of the embodiment of Fig. 2 illustrating thelever arm.

Fig. 4 is a detail of Fig. 2 illustrating the shape of the cam in planview.

Fig. 5 is a diagram illustrating the operation of the spring on the bellcrank.

As illustrated 'in Fig. l, a small asynchronous motor that may bethree-phased for instance and of the squirrel cage type is fed by thevoltage that is to be controlled automatically.

Its rotor Z is keyed to the shaft I and is given a resistance such thatthe maximum torque is developed at zero speed, said torque to correspond"to the required thrust. The motor will produce a torque that is, exceptfor the ohmic drop in potential, a function of the square of the voltagefed "to the rotor.

To one end of the "rotor shaft is keyed the hub 5 to which is securedthe end of a spirally avound torsion spring 6 the outer end of which isrigid with a frame 7 secured to the flange of the casing 8; thetensioning of the spring at the start is obtained through the rotationof said frame. The itorquedeveloped by said spring opposes theelectrodynamic torque developed by :the rotor.

Obviously up to a certain value of the voltage feeding it, the rotorremains stationary and beyond said value the shaft I begins rotating inits bearings 9 and Ill and develops a torque equal to the difference"between its own torque and that of the counteracting spring.

The other end of the shaft is connected to a screw and nut 3, A orsimilar means, the screw 3 being pinned to the shaft while the nut d isadapted to slide in a bore of the hub H, but it cannot rotate by reasonof the key I2 connected to the nut and sliding in the keyway E3 of thehub II.

The resultant of the electrodynamic torque of the rotor and of thetorque of the counteracting spring causes a forward or rearward movementof the nut d the end of which forms a pusher member adapted to act onthe piled up carbon discs.

Obviously the pressure exerted will depend solely on the difierencebetween the electrodynamic torque and the torque of the counteractingspring regardless of the position of the nut and consequently theangular position of the rotor has no influence on the actual value ofsaid pressure.

In the embodiment illustrated in Figs. 2 to 5, the elementscorresponding to those shown in Fig. 1 have been given the samereference numbers.

I is the shaft to which is keyed the rotor 2 of a small asynchronousmotor the field windings of which have been shown diagrammatically.

ii designates the spirally wound torsional spring that opposes theelectrodynamic torque developed by the rotor. The cam H1 is connectedwith the rotor 2 and has an inner shape (Fig. 4) that is advantageouslya cardioid.

The cam i6 acts on a roller l urged against the cam by the spring iii.For this purpose, the spring 16 is pivotally secured at ii to the leverit while on the other hand the spring is anchored at a stationary pointH). The spring may be suspended at said stationary point, for instancethrough the agency of knives or it may be pivotally secured to a spindleso as to be capable of assuming an angular direction depending on theresultant stress exerted on it.

The lever i8 is formed by a bell crank carrying at one end the roller l5and being pivotally secured at 20 (Fig. 5), for instance, by means ofknives resting on suitable plates. The short arm 2| of the bell crank 18carries a stud 22 by means of which pressure is exerted on the piled upelements 23.

The operation of said arrangement is as follows: under the action of thespring it, when contracted, the stud 22 presses normally on the elementsheaped up at 23. The electrodynamic torque produced by the rotor underthe action of the current passing through the windings of the statorcauses the cam i l to rotate and the roller 15 to move so as to vary thepressure exerted on the heaped up elements at 23.

It will be easily understood that according to the direction of theforces exerted, the heaped up elements are subjected to compression orrelease. If said heaped up elements are inserted for instance in thefield circuit of a generator, the voltage of which feeds the smallasynchronous motor, an automatic regulating action in the directionrequired for correcting any variation in the voltage will be provided.

It is obvious that in an arrangement of this type, the torque dependschiefly on the voltage feeding the motor so that resistance Variationsdue for instance to variations in temperature constitute a disturbingfactor of secondary importance only.

If in the arrangement disclosed a polyphase induction motor is used andconnected to the poly- 4 phase A. C. system, the voltages of thepolyphase system, even if the phase voltages are unequal for which theterm "unbalanced is com" monly used, will be kept at an average value.

Consequently, if the generator is called upon to feed an unbalanced loadwhile the regulator depends on the resultant of the fields produced bythe 3 or N phases, the regulation will be executed with respect to theaverage value of the voltages of the different phases. This shows theadvantage of my improved regulator over known regulators allowing actiononly on a single phase which could lead to the necessity of inserting aregulator in each phase.

Where it is desired to control a single phase system, the samearrangements are applicable whereby a single phase induction motor isused as a regulator, an auxiliary phase being provided in said motor fedwith current that is phase shifted through an induction coil or acapacitor.

It is also possible to provide in the stator of the asynchronous motornot only one but two or more windings that may be fed with voltages orcurrents having the same frequency but not necessarily the same phase.The torque on the rotor shaft of the motor will be the resultant of thedifferent superimposed torques. Such an arrangement is applicable forinstance to the parallel operation of several generators.

In case of direct current, the control device may include a rotor with aconstant gap having a series or shunt field according to thecharacteristic desired for the variations of the driving torque withreference to the electric quantity governing the D. C. feed.

With a view to avoiding the need of a commutator, of brushes andassociated parts, the armature winding may be tapped at two points oreven consist of cross coils, with the feed provided through flexibleleads or through the springs balancing the torque.

Under such conditions, for a predetermined feed voltage, theelectrodynamic torque varies obviously as a function of the sine betweenthe rotor winding and the inducing field; however, it is certain thatfor a substantial angular shifting of the rotor Winding to either sideof its position of maximum torque, the sine of the angle varies butlittle and consequently the thrusts necessary for the action on thepiled up discs may be practically constant over a wide range regardlessof the angular position of the rotor.

The counteracting spring may be a, coiled or a torsion spring of anysuitable shape or it may be associated with a further spring actingthrough compression or contraction and inserted between the pushermember and the piled up discs. The transformation of the angularshifting of the rotor into a linear movement to act on the piled updiscs may be achieved, for instance, by means of a connecting rod andcrank pin arrangement, the axis of the piled up discs being positionedif required in a plane that is not parallel to the axis of the motor, itis also possible to use a system including a cam and cam followers movedby the motor shaft and acting on the piled up discs through a lever orsimilar transmission means.

What I claim is:

1. A method for applying a variable pressure on a stack of carbonelements forming a resistor influencing an electrical current to beregulated, comprising causing said current to developelectrodynamically, in combination with a magnetic circuit, thereluctance of which is constant, a

static deflecting torque depending solely on characteristics of saidcurrent, and causing said torque to produce on the resistance a pressurethe value of which depends solely on the turning movement of saidtorque.

2. System for applying a variable pressure in an electric regulator on astack of carbon elements forming a resistor influencing an electricalcurrent to be regulated, comprising in combination with said resistance,an electric motor in cluding a stator, a, rotor and a rotor shaft, saidmotor establishing an inductive field having a constant reluctance,means for feeding said motor with the current to be regulated, resilientmeans arranged to act on the rotor shaft in opposite direction todeflecting torque produced in the motor, means for transforming thedeflecting movement of the rotor into a translational movement, andmeans to transform the translational movement into pressure against theresistance elements, the value of the pressure depending solely on thevalue of the characteristics of the current developing the rotor torque.

3. System for applying a variable pressure in an electric regulator on astack of carbon elements forming a resistor influencing an electricalcurrent to be regulated, comprising in combination with said resistance,an electric motor including a stator, a rotor and a rotar shaft, meansfor feeding said motor with the current to be regulated, resilient meansacting on the rotor shaft in opposite direction to the electrodynamictorque produced in the motor, a threaded member coaxial with and rigidlysecured to the motor shaft, a nut engaging said threaded member, meansfor preventing said nut from rotating, and means to transform thelongitudinal movement of the nut into pressure on the resistanceelements, the value f the pressure depending solely on the value ofcharacteristics of the current developing the rotor torque.

4. System for applying a, variable pressure in an electric regulator ona stack of carbon elements forming a resistor influencing an electricalcurrent to be regulated, comprising in combination with said resistance,an electric motor including a stator, a rotor and a rotor shaft, meansfor feeding said motor with the current to be regulated, resilient meansacting on the rotor shaft in opposite direction to the electrodynamictorque produced in the motor, a cam rigidly carried by the rotor shaft,a bell crank, a stationary pivot for the apex thereof, a roller carriedby one end of the bell crank and engaging the cam. a spring supported atone end and pivotally secured at its other end to the bell crank forurging said roller against the cam, and means at the other end of thebell crank to exert pressure on the resistance elements.

5. A method for applying a Variable pressure on a stack of carbonelements forming a. resistor influencing an electrical current,comprising causing said current to develop by electromotive principles astatic deflecting torque depending solely on characteristics of saidcurrent, mechanically setting a force in opposition to said torqueaccording to the desired value to be regulated, and producing a variablepressure on the resistor, the pressure changes being solely depending onthe deflecting torque.

MARCEL MUSSO.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,503,085 Blake July 29, 19241,892,054 I-Iinchman Dec. 2'7, 1932 1,955,111 Buckler Apr. 17, 19342,015,468 Brown et al Sept. 24, 1935

